Method of forming a dielectric cap layer for a copper metallization by using a hydrogen based thermal-chemical treatment

1. A method, comprising:

forming a copper based metal region in a dielectric layer of a metallization layer of a semiconductor device, said copper based metal region having an exposed surface;

cleaning said exposed surface by means of a thermal-chemical treatment performed in a hydrogen-containing gaseous ambient, wherein the thermal-chemical treatment is thermally initiated in the absence of a plasma by heating said copper based metal region;

modifying the cleaned surface in a thermal treatment on the basis of a silicon-containing precursor to form a modified surface comprising copper silicide, wherein said modification is performed in the absence of a plasma; and

depositing a dielectric cap layer on said modified surface.

2. The method of claim 1 , wherein depositing said cap layer is performed in situ with said modifying of the cleaned surface by establishing a plasma immediately after modifying the cleaned surface.

3. The method of claim 1 , wherein said cap layer is deposited on the basis of a silicon-containing precursor material.

4. The method of claim 1 , wherein said hydrogen-containing gaseous ambient is established by supplying hydrogen and at least one nitrogen-containing gas into said gaseous ambient in the absence of a plasma.

5. The method of claim 4 , wherein a supply of hydrogen is discontinued after modifying said cleaned surface.

6. The method of claim 4 , further comprising supplying an inert carrier gas other than nitrogen into said gaseous ambient.

7. The method of claim 6 , wherein said inert carrier gas comprises helium and said cap layer is deposited on the basis of 3MS.

8. The method of claim 1 , wherein modifying said cleaned surface and depositing said cap layer are performed on the basis of the same process parameters except for a supply of hydrogen.

9. The method of claim 3 , wherein said silicon-containing precursor gas comprises at least one of silane, 3MS (tri-methyl silane) and 4MS (tetra-methyl silane), and wherein a degree of diffusion of the silicon-containing precursor into the exposed surface is controlled by adjusting process parameters of the silicon-containing precursor gas in the absence of a plasma.

10. A method for forming a dielectric cap layer in situ, the method comprising:

cleaning an exposed surface of a copper based metal region in a dielectric layer of a metallization layer of a semiconductor device by means of a thermal-chemical treatment performed in a hydrogen-containing gaseous ambient, wherein the thermal-chemical treatment is thermally initiated in the absence of a plasma by heating said copper based metal region;

modifying the cleaned surface in a thermal treatment on the basis of a silicon-containing precursor to form a modified surface comprising copper silicide, wherein said modification is performed in the absence of a plasma;

establishing a pre-deposition ambient including a silicon-containing precursor gas in the absence of a plasma, and

depositing the dielectric cap layer on said modified surface in said pre-deposition ambient by generating a plasma therein.

11. The method of claim 10 , wherein said hydrogen-containing gaseous ambient is established by supplying hydrogen as the only process gas.

12. The method of claim 10 , wherein said hydrogen-containing gaseous ambient is established by supplying hydrogen and at least one further process gas in the absence of a plasma.

13. The method of claim 12 , wherein said at least one further process gas comprises at least one of nitrogen and ammonia (NH 3 ).

14. The method of claim 10 , wherein a supply of hydrogen is discontinued when modifying said cleaned surface.

15. The method of claim 10 , wherein establishing said pre-deposition ambient comprises discontinuing supply of process gases and reducing residues of said process gases by pumping.

16. The method of claim 15 , further comprising supplying process gases for establishing said pre-deposition ambient for a specified time period for stabilizing said pre-deposition ambient.

17. The method of claim 10 , wherein establishing said pre-deposition ambient comprises discontinuing the supply of hydrogen and supplying process gases for said pre-deposition ambient without performing an intermediate pump process.

18. A method, comprising:

providing a semiconductor device comprising a substrate having formed thereon a copper based metal region having an exposed surface;

pre-treating said exposed surface in the absence of a plasma ambient to prepare said exposed surface for receiving a capping layer, said pre-treating comprising performing a surface cleaning process in a hydrogen-containing gaseous ambient and performing a surface modification process on the basis of a silicon-containing precursor to form a modified surface comprising copper silicide, and wherein the surface cleaning process is thermally initiated in the absence of a plasma by heating the copper based metal region; and

depositing in situ said cap layer in the presence of a deposition ambient and a plasma.

19. The method of claim 18 , wherein said cap layer is deposited immediately after said surface modification process without an intermediate process step for establishing a pre-deposition ambient.

20. The method of claim 19 , wherein depositing said cap layer comprises discontinuing supply of hydrogen gas to said deposition ambient.

21. The method of claim 18 , wherein pre-treating said exposed surface comprises establishing a pre-deposition ambient in the absence of a plasma after performing said surface modification process.

22. The method of claim 21 , further comprising discontinuing supply of process gases and performing a pump step prior to establishing said pre-deposition ambient.